Mercury modulation of GABA-activated chloride channels and non-specific cation channels in rat dorsal root ganglion neurons.

The effects of mercuric chloride and methylmercury chloride on the rat dorsal root ganglion neurons in primary culture were studied by the whole-cell patch clamp technique. gamma-Aminobutyric acid-induced chloride currents were augmented by mercuric chloride in a potent and efficacious manner; at concentrations of 1 and 10 microM, the current amplitude was increased to 130% and 200% of the control. Methylmercury even at 100 microM did not augment but rather decreased the GABA-induced chloride current. Both mercuric chloride and methylmercury generated slow inward currents by themselves. These currents are not mediated by the GABA-activated chloride channels or by voltage-activated sodium, potassium or calcium channels, and are likely to be due to non-specific cation channels.